Documentation:
Image Box

Images can include a title which can be loaded dynamically from the media attachment or entered manually.

Title

Here you can select the source of the title text. There are six options:

1. None
2. Title Text
3. Alternative Text
4. Caption
5. Description
6. Custom

When Title Text or Alternative Text is selected, values from the Attributes toggle will be used first. If no values are found there, values will be taken from the media attachment. When Caption or Description is selected, values will always be taken from the media attachment.

See here for more details.

Custom Title

Here you can enter a custom title.

See here for positioning the title.

See here for styling the title.

See here for an example.